Is Slutting Around Good For the Species?

Coming hard on the (possibly spike) heels of my post on the sexually-transmitted HPV virus and the new Gardasil vaccine is a question for the ages:

If being promiscuous is so damned bad, why hasn’t it been bred out of the human species over the millennia through natural selection?

Sam de Brito, the answerer of deep questions at the delightful All Men Are Liars blog in Australia, responds thusly:

"If remaining monogamous was truly an evolutionary plus, why are we not seeing a higher variant of humanity for whom rooting around is not an issue; because when they mate, they imprint on each other so profoundly that they cease to find alternative mates sexually exciting?

"Some animals (penguins, swans, mallard ducks) have managed this evolutionary leap, so why are we dragging the chain?

"Perhaps the answer is because 'slutting' around is actually good for the species."

More here.